When circuit breakers are connected within electrical power systems for protecting the main and branch circuits, it is necessary to periodically determine whether the circuit breakers are operating properly. With electronic type circuit breakers employing an analog circuit processor such as described within U.S. Pat. No. 4,266,259 a field-test kit is temporarily connected with the electronic trip unit circuit to test the overcurrent response of the individual circuit breakers connected within the system. U.S. Pat. No. 4,105,965 describes one such test kit employed with electronic circuit breakers which contain an analog signal processor within its trip unit circuit. U.S. Pat. No. 4,128,804 describes a field-test kit used with electronic circuit breakers employing an analog signal processor within the trip unit circuit along with a ground fault sensing circuit, to inhibit a ground fault trip function, when the test kit circuit is performing a single-phase current test.
With electronic circuit breakers employing digital signal processors within the trip unit circuit, such as described in U.S. Pat. No. 4,351,013 and U.S. Pat. No. 4,672,501 entitled "Circuit Breaker and Protective Relay Unit", it is convenient to include a self-test program within the microprocessor connected within the trip unit circuit.
With electronic circuit breakers such as described in U.S. Pat. Nos. 4,589,052 and 4,649,455 which employ a digital processor in the trip unit circuit but do not employ a microprocessor, per se, an external test kit is used to determine the operating parameters and response characteristics of the trip unit circuits. All of the aforementioned U.S. Patents are incorporated herein for reference purposes. One purpose of the instant invention is to describe a test kit and test circuit that is capable of testing electronic circuit breakers employing either a digital processor or an analog processor within the trip unit circuit.